The Temperature Dependence of the Coefficients of Thermal and Isothermal Slip of a Diatomic Gas with Rotational Degrees of Freedom

A model kinetic equation is suggested for diatomic gases with rotational degrees of freedom of molecules. The free parameters of the model are related to Eucken's partial factors. This model is used to solve the problem on the slip of a diatomic gas along a plane surface. The coefficients of thermal and isothermal slip are obtained in the form of functions dependent on the transport coefficients and the frequency of inelastic collisions of gas molecules and, as a consequence, on the temperature.     

Kinetic Coefficients in the Boundary-Value Problem on the Slip of a Multiatomic Gas with Rotational Degrees of Freedom

The boundary-value problem on the slip of an inhomogeneous multiatomic gas along the spherical surface of small curvature is solved. For this purpose, a model kinetic equation that includes the rotational degrees of freedom of molecules is proposed. The solution is performed using the method of half-space moments. Gas-kinetic slip coefficients and jumps of macroscopic parameters of gas of the first and second order in the Knudsen number are obtained. These gas-kinetic coefficients are represented in the form of functions depending on the accommodation coefficient of tangential momentum, on the accommodation coefficients of the translational and rotational components of energy, and on the Prandtl number. For a number of multiatomic gases, calculations of the above-mentioned coefficients are performed.     

A Ground State Monte Carlo Approach for Studies of Dipolar Systems with Rotational Degrees of Freedom

We have developed a path integral ground state Monte Carlo (PIGSMC) algorithm for quantum simulations of rotating dipolar molecules, using a highly accurate sixth-order algorithm. The method allows us to calculate unbiased estimates of ground state properties of dipolar molecules in a variety of geometries, with or without an external electric field. To demonstrate the capability of the approach, we calculate the orientational phase diagram of a one dimensional lattice system of rotating point dipoles in the absence of any external electric fields. We find that for finite lattice size, this system exhibits an order?Cdisorder transition at finite dipolar interaction strength in contrast to the well-known orientational disorder of the corresponding one dimensional O(3) quantum rotor models. Comparison of the quantum Monte Carlo results with a self-consistent field estimate of the phase transition shows the emergence of an ordered phase at non-zero dipolar strength, confirming the symmetry breaking role of the anisotropic dipole?Cdipole interaction.     

Degrees of Freedom for Chi-Square

In this paper we have obtained the maximum likelihood estimates of the fraction defective (p) when data from the curtailed sampling plans are subject to misclassification. We have assumed that the inspector classifies a defective as a nondefective when the kth defective appears at the kth inspection. The maximum likelihood estimate of the probability of misclassification is also obtained. The asymptotic variances and covariances of these estimates are derived. A numerical example is provided.     

Gabor's Signal Expansion and Degrees of Freedom of a Signal

Gabor's expansion of a signal into a discrete set of properly shifted and modulated versions of an elementary signal is introduced, and a way to determine the expansion coefficients is derived. The way in which the expansion coefficients are transformed when the signal propagates through a linear system, is described; in particular, the basic coherent-optical system consisting of a 4farrangement with rectangular apertures in the input plane and the Fourier plane, is considered. As a result, the well-known property that a signal which is roughly limited both in space and in spatial frequency has a number of complex degrees of freedom which is equal to the space-bandwidth product, is re-established.     

两自由度和三自由度线性振动系统的特征亏损

着重讨论两自由度和三自由度非比例阻尼系统的特征亏损结构,得到一些有用的结果,举出一些可实现的亏损系统实例,为实验观测振动系统特征亏损现象打下基础.     

Development of a Spherical Induction Motor With Two Degrees of Freedom

This paper reports on the development of a spherical actuator with two actuated degrees of freedom (DOFs). The electromechanical conversion principle is that of an induction motor. The paper first discusses possibilities of adapting the actuator to a spherical rotor actuated with an unlimited angular range along two DOFs. These concepts are then characterized and compared by analytical and numerical modeling, and the final shape of the actuator, composed of a two-layer rotor with teeth surrounded by five inductors, is described. A prototype has been built, and its performance, in terms of characteristic torque-speed and efficiency, has been measured.     

High-Temperature and Nonequilibrium Partition Function and Thermodynamic Data of Diatomic Molecules

Accurate molecular partition functions are required to determine both thermodynamic properties for equilibrium and nonequilibrium flow field calculations, and energy level populations for radiative heat transfer in high enthalpy flows, for instance. Thermodynamic functions of diatomic molecules are computed in this study at high temperatures and for nonequilibrium media in the framework of multi-temperature models. Partition functions, average energies, and specific heats of N₂, , NO, O₂, CN, C₂, CO, and CO⁺ are calculated up to 50,000 K by direct summation over energy levels using recent and accurate spectroscopic data and dissociation energy values. Estimates are made for the error introduced by neglecting the highest considered electronic states. For nonequilibrium media, the sensitivity of the multi-temperature thermodynamic functions to different schemes for energy partitioning is discussed. In particular, the effects of vibration–rotation coupling are investigated. The tabulated results are available upon request.     

七自由度缓冲衬垫包装的动力学仿真

目的针对常用四角衬垫的七自由度包装衬垫进行动力学分析,为以后用该类型衬垫仿真奠定基础。方法使用Matlab进行编程产生随机高斯白噪声,并进行滤波处理,然后使用ode15s模块对以能量法建立七自由度的衬垫包装系统进行动力学微分方程求解。结果各支脚的垂直振动位移趋势一致,且数值大小低于8 mm,偏转角位移介于0.006~0.008 rad之间,被包装物垂直位移响应低于6~6.8 mm,验证了在该工况下缓冲衬垫的缓冲特性。结论在该激励作用和包装系统的减振作用下,被运输包装物得到了有效的防护,并且线性趋势和实测相吻合,仿真效果良好。     

Thermoelectric GeTe with Diverse Degrees of Freedom Having Secured Superhigh Performance

Driven by the ability to harvest waste heat into reusable electricity and the exclusive role of serving as the power generator for deep spacecraft, intensive endeavors are dedicated to enhancing the thermoelectric performance of ecofriendly materials. Herein, the most recent progress in superhigh‐performance GeTe‐based thermoelectric materials is reviewed with a focus on the crystal structures, phase transitions, resonant bondings, multiple valance bands, and phonon dispersions. These features diversify the degrees of freedom to tune the transport properties of electrons and phonons for GeTe. On the basis of the optimized carrier concentration, strategies of alignment of multiple valence bands and density‐of‐state resonant distortion are employed to further enhance the thermoelectric performance of GeTe‐based materials. To decrease the thermal conductivity, methods of strengthening intrinsic phonon–phonon interactions and introducing various lattice imperfections as scattering centers are highlighted. An overview of thermoelectric devices assembled from GeTe‐based thermoelectric materials is then presented. In conclusion, possible future directions for developing GeTe in thermoelectric applications are proposed. The achieved high thermoelectric performance in GeTe‐based thermoelectric materials with rationally established strategies can act as a reference for broader materials to tailor their thermoelectric performance.     

测量不确定度的自由度的计算

在不确定度的评定过程中,有时需要计算自由度。本文将就如何理解自由度,特别是如何理解B类评定的标准不确定度的自由度,以及如何计算A类评定的标准不确定度的自由度、B类评定的标准不确定度的自由度,合成标准不确定度的有效自由度等。     

Inhomogeneous States in Strongly Correlated Electron Systems with Orbital Degrees of Freedom

We study a strongly correlated electron system with charge carriers characterized by different values of orbital quantum number. It is shown that such a system exhibits a tendency to phase separation owing to a competition between the charge localization in the orbitally ordered state and metallicity. The effect of orbital ordering on the phase separation is studied employing a minimal model including itinerant charge carriers at the orbitally ordered background. It is shown that at low doping, the phase separation may appear in systems with orbital degeneracy even without taking into account the magnetic structure. We considered this effect using two versions of the model. In the first one, we assumed that in the absence of doping, the orbital structure results from the interaction of core electrons with the lattice. Electrons appearing due to doping move in this background. In an alternative model, the same electrons take part in the formation of both band structure and orbital ordering.      

关于不确定度评定中自由度的定义与估算

本文详细叙述了自由度的定义、不确定度与自由度的关系及其估算方法。     

具有刚度非线性双层隔振系统冲击响应数值分析研究

对双层隔振系统中的弹性元件即隔振器采用非线性立方刚度模型描述,在此基础上建立了双层隔振系统的动力学方程。应用Runge-Kutta数值法求得系统的冲击响应,分析了双层隔振系统上下层质量之比、刚度之比以及隔振器阻尼和硬特性刚度系数对系统抗冲击性能的影响,对双层隔振系统的抗冲设计具有一定的参考意义。     

弹性轨道上二自由度磁悬浮列车的动力特性分析

通过对弹性变形轨道上二自由度磁悬浮列车耦合系统动力特性的数值研究,给出了系统受控稳定性情形下控制参数G1,G2 的选取方式;讨论了控制参数G1,G2 和系统特征参数(如悬浮体质量Ms、运行速度v、轨道跨长L等)对磁悬浮系统的动力学特性的影响方式,分析了弹性轨道的变形特征等。     

Collisions between Liquid Drops of Various Shapes in a Gas Flow

Technical Physics Letters - We have experimentally studied the interaction between water drops of various surface configurations moving in a gas medium. Results of high-speed video monitoring...